Arrangement in cranes to determine the deviation of the hoisting device of the crane from a defined vertical line

ABSTRACT

To determine the deviation of the hoisting device of a crane from a vertical line, a light emitting arrangement is placed on the crane which emits a wide beam of light downwardly. Within this beam, the hook or other hoisting device has an upwardly directed reflector. There is also on the crane a detector unit which receives the light reflected from the reflector and emits a signal which indicates the deviation of the hoisting device from the vertical.

United States Patent [191 Lenander et al.

in] 3,826,380 [451 July 30, 1974 ARRANGEMENT IN CRANES TO DETERMINE THEDEVIATION OF THE HOISTING DEVICE OF THE CRANE FROM A DEFINED VERTICALLINE [75] Inventors: Bo Lenander; Bernt Ling, both of Vasteras, SwedenAssignee: Almanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden Apr.12, 1973 Appl. No.: 350,623

[22] Filed:

[30] Foreign Application Priority Data Apr. 14, 1972 Sweden 4859/72 [52]U.S. Cl 212/125, 212/11, 340/282 [51] Int. Cl. B66c 19/00 [58] Field ofSearch... 212/10, 21,11, 39 R, 39 MS,

[56] References Cited UNITED STATES PATENTS 2,948,890 8/1960 Barth eta1. 340/282 X 3,517,830 6/1970 Virkkala 212/21 X 3,544,988 12/1970Astheimer 340/282 3,750,130 7/1973 Lute 340/267 C PrimaryExaminer-Richard A. Schacher Assistant Examiner.1ames L. Rowland 57ABSTRACT To determine the deviation of the hoisting device of a cranefrom a vertical line, a light emitting arrangement is placed on "thecrane which emits a wide beam of light downwardly. Within this beam, thehook or other hoisting device has an upwardly directed reflector. Thereis also on the crane a detector unit which receives the light reflectedfrom the reflector and emits a signal which indicates the deviation ofthe hoisting device from the vertical.

12 Claims, 6 Drawing Figures PATENTEDJULBOISM SHEET 1 BF 3 Fi'g/BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to an arrangement for cranes to determine thedeviation of the hoisting device of the crane from a defined verticalline.

2. The Prior Art When goods are being loaded with the help of cranes,for various reasons undesirable oscillations of the hoisting device ofthe crane, to which the load is attached during hoisting and transport,occur. These oscillations may be of a magnitude of :t 500 mm and have aduration of sec, which considerably increases the time required for aloading or unloading cycle since the load cannot be lowered until theoscillations fall below a certain amplitude. When stacking containers,for example, the oscillation amplitude must in certain cases be lessthan i 25 mm.

It is therefore extremely important to reduce or even a completelyeliminate these oscillations during the travelling stage of the crane sothat, when the crane is in the desired final position, the movements ofthe hoisting device have been reduced to an acceptable level for ahoisting or lowering movement. The time required for a work phase cantherefore be kept to a minimum. In order to achieve this reduction ofthe oscillations, measuring equipment is required to record parameterssuch as oscillation amplitude, the speed of the hoisting device inrelation to the crane trolley, cable length, and other variables, andsuch measuring equipment must be rapid, accurate and reliable.

SUMMARY OF THE INVENTION The object of the present invention is toprovide a means, with the help of which parameters of a describedoscillating sequence can be measured and which can be utilized tocontrol a system for reducing such oscillations.

The arrangement according to the invention'is characterized in the factthat the crane carries an arrangement for emitting downwardly a lightbeam of considerable width, within the field of which lies an upwardlyreflecting device carried by the gripping device or hook. The crane alsohas a detector unit composed of a lens and a light sensitive member inthe path of the upwardly reflected light and responsive to changes inthe direction of light to indicate deviation from the vertical line.

If, in accordance with the device according to the invention, all activeand sensitive parts of the measuring equipment are placed on the craneand the hoisting device only comprises passive, compact, easily-handledelement having no direct contact with the active part of the equipment,considerable advantages are gained in comparison with an arrangement inwhich the detector unit is placed on the hoisting device. This would,for instance, require special signal wiring between the crane and thehoisting device. Special regulations would then apply since this signalwiring would run in the vicinity of high-voltage cables. Such signalwiring is subject to dirt and wind and must therefore be provided withsome form of stabilizer to prevent it from being blown in among thehoisting cables of the crane and also to gather it up when the hoistingcables are shortened. There must also be some form of container on thehoisting device for this purpose, which takes up considerable space.Equipment on the hoisting device is also likely to become dirty.Furthermore, additional equipment on the hoisting device requires morespace and increases the weight and a measuring unit placed on thehoisting device therefore limits the range of application, for exampleto handling containers, so that the hoisting device can be constructedto cater for specific requirements.

BRIEF DESCRIPTION OF THE DRAWINGS The device according to the presentinvention will be further described with reference to the accompanyingdrawings, in which FIG. 1 shows a crane with trolley and hoisting deviceon which the device according .to the invention is placed,

FIG. 2 shows in detail the ray path of the detector unit included in thedevice according to the invention,

FIGS. 3a and 3b show the principle of a retroreflector,

FIG. 4 is a diagram of the light-sensitive surface of the photo-detectorand FIG. 5 shows an example of an evaluation device included in thedevice according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows atrolley l2movable in the directions 11 on a crane beam 10. A hoisting device 14 issuspended from the trolley 12 by means of cables 13. A load may beapplied on the hoisting device 14, to be hoisted and transported. Thedevice according to the invention comprises an active unit 15 arrangedon the lower side of the trolley 12, and a passive unit in the form of aretroreflector 16 arranged on the upper side of the hoisting device 14.

The main parts of the active unit 15 constitute a light emitter 17, acollecting lens 18 and a detector 19, as can be seen in FIG. 2.

The function of a retroreflector can be seen in.FlGS. 3a and 3b. Aretroreflector 16 consists of three similar reflecting surfaces 20, 21and 22, in the same configuration as the corners of a cube. A light ray24 reflected by the retroreflector is always parallel to the light ray23 falling on the retroreflector 16 and the reflected light ray 24leaves the retroreflector 16 at a point diagonally opposite the point ofentry. The retroreflector 16 can be rotated about arbitrarily directedaxes of totation through its point without altering the distance betweenthe approaching and reflected light rays.

The operation of the device according to the invention will now bedescribed with referenceto FIGS. 1, 2, 4 and 5.

The light emitter 17, the optical axis of which is suitably arranged tocoincide with the optical axis of the lens 18, the mid-point normal tothe light sensitive surface of the detector 19, and with the verticalline 25 for the hoisting device 14 when this is in its rest position,emits a diverging light bundle 26 in the direction of the hoistingdevice 14, whereupon some of the light 26 emitted is reflected by theretroreflector 16 towards the active unit 15, parallel to the raysapproaching the retroreflector 16. The reflected light falls on thecollecting lens 18 arranged immediately above the light emitter 17. Thelens 18 breaks down the light falling on it on the light-sensitivehorizontal surface 27 of the detector 19.

The light emitter 17 has preferably such divergence that it covers thearea within which the retroreflector 16 is expected to move and thediameter of the lens 18 is preferably twice as'large, or even more, thanthat of the retroreflector 16 so that all light which comes into contactwith the retroreflector 16 will be thrown back through the lens 18 andprojected on the detector 19 The light emitter 17 preferably consists ofa light diode which is fed by pulses from an oscillator 30. Pulsing isused in order to easily distinguish between light received by thedetector 19 from the retroreflector 16 and other irrelevant light.

The detector 19 preferably consists of a linear photodetector having twoaxes with the ability to sense the focal point of the projected light,thus making good focus'singof the light on the detector 19 unnecessary.

An example of such a detector is UDT SC/25, produced by United DetectorTechnology, Inc., US.

The mentioned photo-detector UDT SC/25 has a light-sensitive surface 27,as can be seen in FIG. 4. On this surface 27 two axes 28, 29 are marked,to one of which output signals obtained from the photo-detector arerelated.

When the retroreflector 16 (that is, the hoisting device 14) has moved adistance X from the vertical line 25 with an angle of oscillation a, thefocal point of the light projected by the lens 18 onto thelight-sensitive surface 27 of the detector 19 becomes displaced.

If theline length in question is equal to S and the projection of theline length on the vertical line 25 is equal to S, then when a l (inpractice a 2.5")

tan a X/S X/S and when the distance between the lens 18 and the detectoris Z, then 0 tan a Y/Z which gives Thus, if the line length S can bemeasured continuously and if the distance Z between the lens 18 and thedetector 19 is constant and known, the output signals fromthe detector19, after evaluation, can be used as input signals for a control systemwhich controls the relative movement between the hoisting device 14 andthe trolley 12.

The line length S is measured continuously by a potentiometer unit, forexample, (not shown) arranged on the trolley 12.

When UDT SC/25 is used as detector 19, two output signals are obtainedin the form of voltages U, and U the magnitudes of these depending onthe deviation of the focal point of the light falling on the detectorsurface 27 from one of the axes 28 or 29. In order to obtain a directmeasurement of the deviation Y of the focal point, the signal U,/( U, Uis obtained, or the signal U /(U, U,). The position of the vertical line25 then corresponds to U, U

Signals 31 and 32 obtained from the detector 19 are conveyed to filters33 and 34, respectively and amplifiers 35 and 36, respectively, afterwhich the pure signals U, and U, are obtained. Both the signals U, andU, are supplied to an amplifier 37 and added to give the signal U, UThis latter signal, together with one of the signals U, or U,, in thiscase U,, is supplied to a di- 4 vider 38, thus producing the signal It,U,/(U, U,,) where k, is a constant dependent on the divider. The signalk, U,/(U, U is supplied, together with a signal U,,,, to an amplifier39. The signal U now has the value k, l/2, that is, it represents thesignal k, U,/ (U, U when U, U

that is, the deviation X 0.

By the indicated addition a signal It, Y is obtained from the summator39 where Y is the deviation of the focal point of the light falling onthe detector 19 from the mid-point of the detector 19 and k, is aconstant.

Signal k Y is supplied to a multiplicator 40, together with themomentary value of the line length, whereupon'a signal It, S Y isobtained.

A signal is thus obtained which directly carries information concerningthe deviation of the hoisting device 14 from the vertical line 25, andwhich can be supplied to a member controlling the relative movementbetween trolley 12 and hoisting device 14.

The summation signal U, U, is preferably used for other purposes also.

The signal U, -.l- U, can also be used to control the output intensityof the light emitter 17, that is the light diode, when conditions suchas variation in line length and weather cause the signals U, U to differon different occasions.

In order to adjust the output capacity of the light diode to saidvariations, the signal U, U, is fed together with a reference signal Uto an amplifier 41, the output signal of which constitutes thedifference between said signals. This difference, together with thepulse train from the oscillator 30, controls the output capacity of thelight diode.

The summation signal U, +U is alsoused to detect whether the necessarylight strength is being obtained on the surface 27 of the detector 19 bysupplying the signal U, U, to a level indicator 42 which in turn may beconnected to a signal or indicating device 43, thus preventing falseoutput signals from the device caused by mishaps such as temporaryblocking of the retroreflector 16 by dirt or the like.

As mentioned earlier, the light emitter may comprise a light diode, inwhich case HAFO lA65 is extremely suitable.

Amplifiers may suitably be SL 8018.

The multiplicator and divider may be Nexus 4552, for example and thelevel detector ASEA QDGU 105.

The device described above is not, of course, limited to the embodimentshown, but may be constructed in many ways within the scope of thefollowing claims.

We claim:

1. in a crane, having a hoisting device suspended therefrom, means todetermine the deviation of the hoisting device (14) from a definedvertical line (25), which comprises a light emitter (17) on the crane, alight reflector (16) on the hoisting device (14) and a detector unit(18, 19, 31-43) on the crane, the light emitter (17) including means todirect diverging light (26) towards the hoisting device (14) so that thelight covers a presumed area of movement for the hoisting device (14),the reflector (16) including means to refleet light falling upon ittowards the detector unit (18, 19, 31-43), and the detector unit (18,19, 31-43) including means responsive to such light falling upon it todetect deviations of the hoisting device (14) from said vertical lineand to detect the direction of 4. In a crane according to claim 3, thelight reflector (16) comprising a retroreflector.

5. In a crane according to claim 2, the lens system (18) having ahorizontal aperture which is at least twice as large as the horizontalextension of the light reflector (16).

6. In a crane according to claim 2, the photo-detector (19) having alight-sensitive surface includes means to emit signals (31, 32) whichconstitute a gauge of the deviation of the focal point of the lightconverging on the light-sensitive surface (27) from a defined axis (28)on the light-sensitive surface (27 7. In a crane according to claim 6,the axis (28) defined on the light-sensitive surface (27) of thephotodetector (19) constituting the normal for said vertical line (25).

8. In a crane according to claim 1, the presumed area of movement forthe hoisting device (14) comprising said vertical line (25).

9. In a crane according to claim 1, said vertical line (25) coincidingwith the optical axis of the light emitter (17).

10. In a crane according to claim 9 the optical axes of the lightemitter (17) and the lens system (18) being coincident.

11. In a crane, having a hoisting device suspended therefrom, means todetermine the deviation of the hoisting device (14) from a definedvertical line (25), which comprises a light emitter (17) on the crane, alight reflector (16) on the hoisting device (14) and a detector unit(18, 19, 31-43) on the crane, the light emitter (17) including means todirect diverging light (26) towards the hoisting device (14) so that thelight covers a predetermined area of movement of the housing device(14), the reflector (16) including means to reflect light falling uponit towards the detector unit (18, 19, 31-43), means for measuring thelength of lines (13) running between the crane and said hoisting device,said detector unit (18, 19, 31-43) comprising an evaluating device(31-43) arranged to emit an output signal proportional to the deviationof the hoisting device from said vertical line (25) and proportional tothe direction of said deviation.

12. In a crane, having a hoisting device suspended therefrom, means todetermine the deviation of the hoisting device (14) from a definedvertical line (25), which comprises a light emitter (17) on the crane, alight reflector (16) on the hoisting device (14) and a detector unit(18, 19, 31-43) on the crane, the light emitter (17) including means todirect diverging light (26) towards the hoisting device (14) so that thelight covers a predetermined area of movement for the hoisting device(14), the reflector (16) including means to reflect light falling uponit towards the detector unit (18, 19, 31-43), said detector unit (18,19, 31-43) comprising an evaluating device (31-37, 41) arranted toproduce output signals for controlling the output intensity of saidlight emitter (17).

1. In a crane, having a hoisting device suspended therefrom, means todetermine the deviation of the hoisting device (14) from a definedvertical line (25), which comprises a light emitter (17) on the crane, alight reflector (16) on the hoisting device (14) and a detector unit(18, 19, 31-43) on the crane, the light emitter (17) including means todirect diverging light (26) towards the hoisting device (14) so that thelight covers a presumed area of movement for the hoisting device (14),the reflector (16) including means to reflect light falling upon ittowards the detector unit (18, 19, 31-43), and the detector unit (18,19, 31-43) including means responsive to such light falling upon it todetect deviations of the hoisting device (14) from said vertical line(25) and to detect the direction of such deviation.
 2. In a craneaccording to claim 1, the detector unit (18, 19, 31-43) comprising lenssystem (18) and a photo-detector (19), the lens system (18) projectinglight falling upon it on to the light-sensitive surface (27) of thephotodetector (19).
 3. In a crane according to claim 1, the lightreflector (16) reflecting light parallel to the light falling upon it.4. In a crane according to claim 3, the light reflector (16) comprisinga retroreflector.
 5. In a crane according to claim 2, the lens system(18) having a horizontal aperture which is at least twice as large asthe horizontal extension of the light reflector (16).
 6. In a craneaccording to claim 2, the photo-detector (19) having a light-sensitivesurface includes means to emit signals (31, 32) which constitute a gaugeof the deviation of the focal point of the light converging on thelight-sensitive surface (27) from a defined axis (28) on thelight-sensitive surface (27).
 7. In a crane according to claim 6, theaxis (28) defined on the light-sensitive surface (27) of thephoto-detector (19) constituting the normal for said vertical line (25).8. In a crane according to claim 1, the presumed area of movement forthe hoisting device (14) comprising said vertical line (25).
 9. In acrane according to claim 1, said vertical line (25) coinciding with theoptical axis of the light emitter (17).
 10. In a crane according toclaim 9 the optical axes of the light emitter (17) and the lens system(18) being coincident.
 11. In a crane, having a hoisting devicesuspended therefrom, means to determine the deviation of the hoistingdevice (14) from a defined vertical line (25), which comprises a lightemitter (17) on the crane, a light reflector (16) on the hoisting device(14) and a detector unit (18, 19, 31-43) on the crane, the light emitter(17) including means to direct diverging light (26) towards the hoistingdevice (14) so that the light covers a predetermined area of movement ofthe housing device (14), the reflector (16) including means to reflectlight falling upon it towards the detector unit (18, 19, 31-43), meansfor measuring the length of lines (13) running between the crane andsaid hoisting device, said detector unit (18, 19, 31-43) comprising anevaluating device (31-43) arranged to emit an output signal proportionalto the deviation of the hoisting device from said vertical line (25) andproportional to the direction of said deviation.
 12. In a crane, havinga hoisting device suspended therefrom, means to determine the deviationof the hoisting device (14) from a defined vertical line (25), whichcomprises a light emitter (17) on the crane, a light reflector (16) onthe hoisting device (14) and a detector unit (18, 19, 31-43) on thecrane, the light emitter (17) including means to direct diverging light(26) towards the hoisting device (14) so that the light covers apredetermined area of movement for the hoisting device (14), thereflector (16) including means to reflect light falling upon it towardsthe detector unit (18, 19, 31-43), said detector unit (18, 19, 31-43)comprising an evaluating device (31-37, 41) arranted to produce outputsignals for controlling the output intensity of said light emitter (17).